The drilling of oil and gas wells can be made more efficient if downtime is minimized and hole and drill string problems are eliminated. Drilling fluids or muds are commonly used in the drilling of oil and gas wells to address the abovementioned problems. These drilling fluids serve numerous functions including: (1) cooling the drill bit; (2) lubricating the drill string; (3) cleaning the bore hole; (4) bringing the cuttings to the surface; (5) preventing cavings of the formation by providing hole stability; (6) controlling fluid loss into the formations; and (7) exerting pressure to the sides of the bore hole to prevent the entrance of liquids or gases into the bore hole from the formation being penetrated.
The drilling fluid must have a low fluid loss to prevent excessive loss of fluid into the formation by depositing an impervious filter cake on the sides of the bore hole. The thickness of the filter cake is usually directly proportional to the volume of fluid loss. Therefore, the lower the fluid loss, the thinner the filter cake. Maintaining the diameter of the bore hole being drilled is critical to a successful operation. If the fluid loss is high, then the wall cake will be thick and therefore, the desired diameter of the well bore will be reduced.
Fluid loss additives are commonly used to control the fluid loss and the wall cake thickness of oil and gas wells. The most commonly used fluid loss additives are bentonite clays, polymers, lignites, and surfactants.
Carbon black is basically pure carbon which exists in extremely small particle diameters of approximately 13 to 75 millimicrons. Carbon black particles have a high surface area. The surface area of a carbon black particle is approximately 25 to 500 square meters per gram and has an oil absorptive capacity of 45 to 300 cc per 100 grams.
Carbon black is organophilic and has an extremely high affinity for oils, phenols, alcohols, fatty acids, and other long carbon chain products normally used in drilling fluid.
Carbon black is insoluble and maintains its individual particle identity through mixing and handling procedures commonly used in the drilling mud industry. Carbon black will remain completely stable and finite at temperatures up to 3000.degree. F. The hardness of carbon black, in addition to its high affinity for lubricating substances, makes it an excellent carrier to extremely tight fittings, such as a metal to metal contact. Coated with lubricant, the ultra-fine particle size penetrates openings and surfaces not normally penetrable with other solids in the drilling fluid system.
However, carbon black that has not been chemically treated is basically hydrophobic and will not readily mix with water or water based drilling fluids. Thus, it is difficult to use carbon black as an effective drilling fluid additive.
U.S. Pat. No. 5,114,597 which was assigned to the assignee of this present invention related to a process of manufacturing a drilling fluid containing carbon black in a dispersed state.
Gilsonite, a native asphalt occurring in vein deposits below the surface of the ground, greatly reduces fluid loss and wall cake thickness when properly incorporate with any water based drilling fluid. Gilsonite is commonly found in Utah and Colorado. Gilsonite and other asphaltic type materials penetrate shale pore spaces as a drill bit penetrates a formation. It is assumed that a plastic-flow mechanism will allow the asphaltite to extend into the pores of the shale, thus, reducing fluid loss or mud invasion with a tendency to bond the shale and prevent sloughing. Asphaltite plates out on the bore hole to thereby reduce fluid loss.
However, asphaltite is by nature extremely hydrophobic and will not readily mix with water or water-based drilling fluids. Thus, it is difficult to use asphaltite as an effective drilling fluid additive.
Attempts have been made to make asphaltite-based products more compatible with the drilling fluid. However, none of these attempts have been successful.
Moreover, in typical drilling mud systems, the asphaltic material is packaged in 50 pound bags and dumped into the mud hopper on the rig in amounts equaling from 1 to 50 pounds per barrel of mud. Since the asphaltic material is extremely hydrophobic, a surfactant is then added to the mud system in amounts of 0.5 to 10% by volume to make the asphaltite disperse or become water wet. However, this process is extremely expensive because the surfactant might be used up on other solid materials in the mud system, such as, barite, bentonite, and drilled solids.
Furthermore, the above-mentioned process is very expensive because it does not allow the asphaltite enough retention time with the aqueous phase of the drilling fluid to become dispersed or broken up into individual particles. Therefore, much of the material is lost over the rig shaker after the initial or first circulation through the well bore. Rig shakers can now be operated with shaker screens as fine as 250 mesh with 80-100 mesh being standard. With the above methods of adding asphaltite products dry to the drilling fluid, a conservative estimate of at least 10% or up to 90% of the asphaltite product is screened out and lost over the rig shaker after the first circulation.
U.S. Pat. No. 5,114,598 which was also assigned to the assignee of the present invention related to a process of manufacturing a drilling fluid containing asphaltite in a dispersed state.
Marine or fish oil is a versatile product and finds many applications in the food, feed and technical industries of the world. Like other fats and oils, fish oils consist of a mixture of triglycerides of various long-chain fatty acids with small amounts of mono- and diglycerides, free fatty acids and sterols. The fatty acids that characterize fish oils are similar to those in various vegetable oils and animal fats differing principally in their high proportions of long-chain polyunsaturated fatty acids with five and six double bonds. Marine oils differ among themselves in the percentage of fatty acids. Although the use of fish oil in drilling/completion fluids has been contemplated, there has been no teachings of how fish oils can be incorporated into drilling fluids with improved results. An article entitled "How about fish oil in your mud?" by Robert Garrett was published in Drilling & Completion Fluids, November, 1993 and discussed the need for biodegradable, low-toxicity and earth-friendly materials. However, the article did not discuss how fish oils could be implemented into a drilling fluid.